Bulk is a pet in Battle Run that appears to be a green, buff, giant Humanoid creature. Players ride on it's "pouch" behind its back.
Bulk grants a quick speed boost after it attacks (see below).
Upon activation, Bulk slams his fists into the ground, instantly killing everyone within a mid-sized distance of him.
(Similar to Tank's Cannon Ball and Mr. Touchdown's football explosions or Nacho's Luchador's Pride and Violet's magic)
Bulk is good, but only in certain situations. The prime place to use Bulk is 2nd place, which isn't always where you might be when you get Bulk. Overall, Bulk is still a decent pet.
Bulk is most likely named after the popular movie character, "The Hulk".